SEDIPLASTIC · Microplastic pollution in freshwater sediments: effects at the hydrology, microbial biofilm and thus water quality under global change threats

We live in the “plastic age”. Plastics are key for societal innovation and used on a daily basis. However, due to their ubiquity, persistence, inadequate management & improper waste disposal, they tend to accumulate in the environment. Besides, during their life cycle, they degrade into tiny polluting bits called microplastics (MP<5mm), considered a major environmental threat. Biodegradable plastics (BioMP) have become an alternative since they can be mineralized under certain temperature and moisture conditions. Fluvial sediments and their inherent microbial communities could potentially decompose BioMP due to their role as a nutrient recycling and its high enzymatic activity. However, how the degradation of BioMP will affect nutrient re-cycles in aquatic ecosystems, an essential ecological service, is still unknown. In addition, global change, especially, rising temperature, and hydrologic extreme events, mobilize plastics in freshwater systems and further degrading them into MPs. Thus, there is an urgent need to develop tools to assess, predict and mitigate their effects on freshwater ecosystems. SEDIPLASTIC seeks to explore and provide new knowledge on MP (non- and biodegradable) effects on freshwater sediments under global change conditions. Sediment columns with different grain size, with/without microbial communities, and microparticles (inert, MP, BioMP) will be used. Hydrological parameters, nutrients, dissolved organic carbon, bacterial biomass, viability, and functionality, and MP mobility and degradation will be analysed. Moreover, to better understand the key role of MP in freshwater sediments and how can affect ecosystems services, a predictive model will be developed using project experimental data. Project outcomes will impact beyond academia providing novel tools for industry, government, and thus societal wellbeing. It will contribute to major EU research priorities and to global efforts such as the UN Sustainable Development Goals (6, 12, & 14).